Table 1 Summary of material candidates for transparent neural interface.
From: Transparent neural implantable devices: a comprehensive review of challenges and progress
Material | Composition (Electrode/Substrate) | Electrode Fabrication Method | Electrical Property (Electrode Area) | Transmittance | Biocompatibility | Optical Property Demonstration | Ref. |
|---|---|---|---|---|---|---|---|
Graphene | Nitric acid doped Graphene/Polyimide | Transfer Printing | 541 kohm @ 1 kHz (50 μm × 50 μm) | Transparent above 450 nm | ○ | Calcium Imaging | |
4-layered graphene/Parylene C | Transfer Printing | (243.5 ± 5.9) kohm @1 kHz (~45240 μm2) | >90% (470 nm, 570 nm) | ○ | Fluorescence & OCT imaging Optogenetics | ||
4-layered graphene/Parylene C | Transfer Printing | (248.7 ± 125.0) kohm @1 kHz (17,671 μm2) | N/A | N/A | Fluorescence Imaging | ||
4-layer graphene/PET | Transfer Printing | 963 kohm @ 1 kHz (100 μm × 100 μm) | N/A | N/A | Deep two photon calcium Imaging Optogenetics | ||
CNT | SWCNT/PDMS | Floating catalysis CVD | 0.20 ± 0.03 Mohm @1 kHz (100 μm × 100 μm) | 70–90% (550 nm) | N/A | Two photon Imaging Optogenetics | |
Hydrogel | PVA hydrogel/PDMS | Freeze-thaw | 490 kohm @ 1 kHz (r = 1.5 mm, salt bridge width = 500 um) | 50–60% (400–800 nm) | ○ | N/A | |
Conductive Oxides | ZnO&ITO/Parylene C | Mechanical Dicing/Chemical Etching | ~400 kohm @ 1 kHz/ZnO ~0.15 ohm cm-1/ITO 1.5 kohm cm-1 | >70% (visible light) | ○ | Optogenetics | |
PEDOT:PSS | PEDOT:PSS-EG/PET | Lift-off Spin coating | 50–70 kohm @ 1 kHz (300 μm × 300 μm) | 85% (400–700 nm) | ◎ | Optogenetics | |
Graphene& PEDOT:PSS/Glass | CVD Electroplating | 166 ± 13 kohm @ 1 kHz (r = 15 μm) | 84% (400–700 nm) | N/A | Fluorescence Imaging | ||
Ag | Ag&Au Core Shell/Parylene C | Spray coating Cyan-free Electroless Plating Pin-transfer | 1.1–3.2 ohm cm-2 15 ohm sq-1 (r = 130 μm) | 69–83% (400–700 nm) | ◎ | Optogenetics | |
AgNW&IZO/ Parylene C | Spray coating | 6 ohm sq-1/20 kohm @ 1 kHz (r = 250 μm) | >60% (550 nm) | N/A | Fluorescence Imaging | ||
Au | Au nanonetwork | Nanopattern Electrospinning | 11.8 k-33.9 kohm @ 1 kHz (r = 100 um) | 75–81% (300–1200 nm) | ◎ | Optogenetics | |
Au mesh with PEDOT:PSS/ Parylene dix-SR | Lift-off | 10 kohm @ 1 kHz (PEDOT:PSS 1400 μm2) | 60% (475nm) | N/A | Optogenetics | ||
Au/PEDOT:PSS bilayer/ Parylene C | Lift-off Electroplating | 130 kohm @ 1 kHz (314 μm2) | 70% (550 nm) | ◎ | Two photon Imaging | ||
Au honeycomb grid/ Parylene | Lift-off | 8.14 ohm cm2 /156.6 kohm @ 1 kHz (80 μm × 80 μm) | 70% (550 nm) | ◎ | N/A | ||
Au grid/ ITO bilayer/PET | Lift-off | 5.6 ± 0.7 ohm sq−1 /5.3 k @1 kHz (320 μm × 320 μm) | 59–81% (550 nm) | ◎ | Optogenetics | ||
Au grid/ ITO island/PET | Lift-off | 6.9 ± 0.6 ohm sq−1/20.3 k @ 1 kHz (320 μm × 320 μm) | N/A | ◎ | Optogenetics |
